Mojahed al-Ejla, 8, rests at the Shifa hospital where he is receiving treatment for a fractured skull caused by a July 19 Israeli shelling while he and the family were fleeing from the Shijaiyah neighborhood in Gaza City.

JERUSALEM — U.S. Secretary of State John Kerry said Friday that more work was needed to reach a deal between Israel and Hamas for a seven-day truce in the Gaza war. Israel’s defense minister warned that the military may soon broaden its ground operation “significantly.”

The tough statement by Israeli Defense Minister Moshe Yaalon, coupled with Kerry’s inability to broker even a temporary cease-fire after a week of shuttling around the region, signaled the fighting is likely to drag on, with more than 820 Palestinians and 38 people in Israel killed so far.

In a statement issued shortly after Kerry spoke at a press conference in Cairo, Yaalon’s office quoted him telling troops in the field that “you need to be ready for the possibility that very soon we will instruct the military to significantly broaden the ground operation in Gaza.”

“Hamas is paying a very heavy price and will pay an even heavier price,” Yaalon said. “At the end of the operation, Hamas will have to think very hard if it is worth it to taunt us in the future.”

Israel has said a key objective of its ground operation is to destroy Hamas military tunnels under the Gaza-Israel border — and Israeli media have said the military wants more time to complete the mission.

Of 31 discovered so far, about half have been destroyed. The tunnels, used by Hamas in the past to sneak into Israel, are seen as a strategic threat against Israel.

For days, Kerry has been moving between the Egyptian capital, the West Bank and Jerusalem and talking to officials from Qatar, which is in contact with Hamas. But the most Kerry seemed to have won so far was a willingness from Israeli Prime Minister Benjamin Netanyahu to consider a far less ambitious 12-hour halt in fighting, proposed by U.N. chief Ban Ki-moon.

Netanyahu, Kerry said, “has indicated his willingness to do that as a good faith down payment to move forward.”

Still, Kerry said that the parties are closer than ever to an agreement for a seven-day “humanitarian” truce to start with the Muslim Eid holiday on Monday, ending the holy month of Ramadan.

Speaking alongside the U.N. secretary-general and the Egyptian foreign minister, Kerry insisted that there was a general agreement on the “concept” of a truce but that both sides had concerns over details of carrying it out.

“Gaps have been significantly narrowed,” he said. “It can be achieved, if we work through some of the issues that are important for the parties.”

Gaza fighting continued alongside the truce efforts. Israeli airstrikes hit more than 80 sites in Gaza, while militants in the tiny Mediterranean strip fired 50 rockets at Israel, the army said. Among the sites hit in Gaza were 30 homes, including that of a leader of the Islamic Jihad group who was killed along with his sons, Palestinian officials said.

And unrest sparked by the conflict intensified in the West Bank, where five Palestinians were killed during protests against the Israeli operation in Gaza.

The U.S. top diplomat said the goal of halting fighting for seven days was to provide time to work out further talks to address each side’s demands. He said some “terminology” on a truce’s framework still needed work.

The worst round of cross-border fighting in more than five years has killed 828 Palestinians and wounded more than 5,200, according to Palestinian health officials. The U.N. says civilians make up three-fourths of the dead and a majority of the wounded.

In Israel, 38 people have been killed since July 8, including 35 soldiers, two Israeli civilians and a Thai worker.